Can loose or corroded battery ground cables cause a slow drain on a battery?

I have a '07 Hyundai Azera with a 3.8 L engine. I just recently replaced the battery. The car has started fine over the past month since installing the battery. However, I recently let the car set for approx. Four days while out of town and when I started it up after returning from my trip it was extremely sluggish. I turned it off and restarted it and got the same thing. After driving the car for approx. 45 mins, I turned the engine off and back on a few times and it started very quickly with no hesitation. Every start since then has also been fine, including some after the car has set outside in the cold weather for several hours. Since it is still under warranty, I took it to the dealership and they ran diagnostics on the electrical / charging systems and the only thing that they came back with was that the ground cables were corroded. I'm thinking that this is not the problem. Your thoughts?